The invention concerns a piston pin for a connecting rod in a piston driven internal combustion engine and the design of the friction pairing of the running surfaces of the piston pin and the corresponding connecting rod eye in internal combustion engines as well as a processes for manufacturing piston pins provided with slide layers.
With the development of new generations of engines for motor vehicles, the requirements of the materials employed in the drive aggregate continues to increase. The development of bearings of the drive aggregate, in particular the piston bearings, has not kept pace with the evolving higher mechanical loads, in particular in the long term aspect. The manufacture of suitable piston bearings is as a rule a laborious process.
From DE 19822934 C2 or DE 19822901 C2 a process for application of an external and adhering lubricant layer upon an exposed and tribologically challenged surface of an object is known, wherein the lubricant layer exhibits boric acid (H3BO3) at least under conditions of load. The lubricant layer can also be employed for a connecting rod or piston pin. This type of coating is described in DE 19822932 C1, in which the surface of a connecting rod is coated.
Lubricant coatings have in general the disadvantage, that they wear away with time and lose their effectiveness.
In the manufacture of connecting rods in internal combustion engines it is conventional to provide the connecting rod eyes with slide bearings. Therein the connecting rod eye is as a rule provided with a recessed or seated bearing shell. Recently it has been attempted to replace this shell with slide bearing layers on the inside of the connecting rod.
From DE 19731625 A1 processes are known, for spraying the bearing layer directly on the connecting rod eye by thermal spraying of a bearing material.
Lately slide bearings are frequently formed comprising Al/Cu-alloys, frequently Sn- or Zn-alloy components. From DE 10035032 A1 a process for manufacture of a connecting rod with a bearing layer is known, wherein the bearing layer is applied preferably by means of thermal spray processes, in particular plasma spraying or arc wire spraying and preferably is comprised of Al/Cu-alloys or Cu/(Zn, Al, Sn)-alloys.
DE 19824308 C1 discloses a slide bearing shell with a slide layer applied by electron beam vapor deposition comprising a bonding material of a matrix phase, preferably of aluminum, and a dispersed phase, preferably of Sn, Pb, Bi and/or Sb.